1. Field of the Invention
The present invention relates to a heat-dissipating module. In particular, the present invention relates to a heat-dissipating module including a plurality of serially connected heat-dissipating fan units.
2. Description of Related Art
FIG. 1 is an exploded perspective view of a conventional heat-dissipating module. FIG. 2 is a perspective view of the conventional heat-dissipating module. The heat-dissipating module includes a first fan unit 10 and a second fan unit 20, which are serially connected together to provide an air inlet and an air outlet. The first fan unit 10 is located on the air inlet side, and the second fan unit 20 is located on the air outlet side. Generally, the casing 100 of the first fan unit 10 includes a plurality of engaging notches or grooves 11 and the casing 200 of the second fan unit 20 includes a plurality of engaging tabs 21 for engaging with the engaging grooves 11, thereby serially connecting the first fan unit 10 and the second fan unit 20 together. Thus, an impeller (not shown) of the first fan unit 10 and an impeller 22 of the second fan unit 20 simultaneously drive air, thereby rapidly blowing the air from the air inlet side to the air outlet side.
Although the amount of blown air and the velocity of the air are increased through the use of the above-mentioned heat-dissipating module, several problems still exist. Firstly, cool air can only be sucked into the heat-dissipating module via a single air inlet of the first fan unit 10 on the air inlet side under normal operation of the first fan unit 10 and the second fan unit 20. The overall air output amount is limited. Second, when the first fan unit 10 operates abnormally, the speed of the impeller of the first fan unit 10 is lowered and thus adversely affects the air-blowing efficiency of the impeller 22 of the second fan unit 20 and the overall heat-dissipating efficiency. Third, when the first fan unit 10 or the second fan unit 20 operates abnormally, the air density distribution is not uniform since the air velocity at the impeller of the first fan unit 10 is different from that at the impeller 22 of the second fan unit 20, resulting in poor static pressure-flow rate characteristics and poor P-Q characteristics and generating wind noise.